Issue 60

N. Hassani et alii, Frattura ed Integrità Strutturale, 60 (2022) 363-379; DOI: 10.3221/IGF-ESIS.60.25

a) Mechanical aging with 30% of Rd

b) Mechanical aging with 50% of Rd

c) Hygrothermo-mechanical aging with 50% of Rd

d) Mechanical aging with 70% of Rd

Figure 13: Load-displacement curves obtained for different specimen.

We present in Fig.14 the time evolution of the load-displacement curve of the concrete short column specimens for different level of load applied. First, it can be seen that for the first cycle, load-displacement curves are the same. This indicates that there is no notable damage early in the aging process. This confirms that there is not a high variability of our concrete quality. This agrees well with the statistical analysis of the initial ultrasonic pulse velocity measurements presented above. Second, as the number of aging process increases, the difference between the curves is more notable. This indicates that after several aging process cycles, the degradation was more notable. Fig. 15 shows the time evolution of the load-displacement curve of the concrete short column specimens for different exposure conditions. As observed using Fig. 15, we see that at the start the aging process, load-displacement curves remain the same. In addition, just as observed above, as the number of aging process increases, the difference between the curves grows. To illustrate the behavior of the short concrete column specimens under different loading and exposures conditions, load- displacement curves obtained after the 22 nd aging process, are compared in Fig. 16 to the load-displacement curve of the reference specimen obtained from characterization of the concrete short column specimens. It can be observed that the load-displacement curves obtained after aging process are under the reference specimen curve. This difference can be explained by the loss of the rigidity of specimens due to the degradation that has occurred gradually with the aging process. It can be seen also from the Fig. 16 that this difference increases when level of loading increases, and when we consider a coupled hygrothermal and mechanical aging process.

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